More from WebMD

May 21, 2009 -- Singer Natalie Cole is "resting comfortably" at Cedars-Sinai Medical Center in Los Angeles after undergoing a kidney transplant operation on May 18, according to Cole's web site.

Cole may be able to leave the hospital as early as next week, her spokeswoman tells WebMD.

Cole went public with her hepatitis C in 2008. "Thankfully, her hepatitis C has been completely cured" by treatment given before the kidney transplant, Cole's spokeswoman tells WebMD via email.

Hepatitis C is a liver disease caused by infection with a virus. It damages the liver, which may lead to a need for liver transplant.

But Cole got a kidney transplant, not a liver transplant, and she recently said she believes her hepatitis C treatment was the source of her kidney problems, though she admitted her doctors aren't sure about that.

Natalie Cole's Hepatitis C

During an April 2009 interview on CNN's Larry King Live, Cole said that she was diagnosed with hepatitis C in February 2008 and that she believes she became infected with hepatitis C from illicit drug use years earlier, though she didn't know it. Cole is now sober.

On the show, Cole said she started taking a drug called interferon in May 2008 to fight the hepatitis C virus and that both of her kidneys were failing. She started kidney dialysis.

Cole attributes her kidney problems to her interferon treatment, but says her doctors haven't acknowledged that interferon caused her kidney problems.

"When I talk with my own doctor, he didn't say no and he didn't say yes," Cole said.

"You believe it, though?" King asked her.

"Absolutely, yes; with every bit of my body. I never had a kidney problem in my life," Cole said.

Hepatitis Expert Weighs In

"I think she's mistaken" about interferon causing her kidney problems, says Bruce R. Bacon, MD, director of the division of gastroenterology and hepatology at St. Louis University School of Medicine.

Bacon, who isn't treating Cole and doesn't have details of her case, tells WebMD he doesn’t know of interferon carrying any kidney risks.

"I've [treated] thousands of patients with interferon and not seen any kidney problems from that. I've used it in people with kidney disease, as well," Bacon says.

Bacon notes that a very small percentage of hepatitis C patients, probably less than 5%, develop kidney problems related to their hepatitis.

But he's not sure that's what happened to Cole.

"I don't know that her kidney disease is due to her hepatitis C," Bacon says. "It might be due to blood pressure or diabetes or something else. I just don't know what the cause of her kidney disease is.

"I suspect that what happened was while she was on interferon being treated for her hepatitis C, she had worsening of her kidney function, and it was what we call true-true-and-unrelated. True that she had treatment and true that she had kidney disease, but they were totally unrelated," Bacon says.

Kidney Transplant

As long as Cole's hepatitis C virus is gone, "then she should do fine with the transplant," Bacon says.

Before her kidney transplant, Cole had gotten kidney dialysis three times per week since September.

"In general, kidney transplantation is associated with better patient survival than dialysis, even when you compare patients who remain on the waiting list," Ron Shapiro, MD, professor of surgery and director of the kidney transplant program at the University of Pittsburgh Medical Center, tells WebMD.

"Hopefully, [Cole will] do well and have a good outcome and have the quality of her life be vastly better," says Shapiro, who isn't treating Cole.

Cole's new kidney came from a deceased donor through the regional organ procurement agency, One Legacy, according to Cole's web site.

Most transplanted kidneys come from people who have died, according to background information on the web site of the National Institute of Diabetes and Digestive and Kidney Diseases.

The transplantation operation itself is "a relatively short procedure. It can be on the order of three to four hours, sometimes faster, sometimes longer," says Shapiro. He adds that unlike a transplanted heart, lung, or liver, it can be OK if transplanted kidneys don't work immediately after the transplant.

Cole will need to take immune-suppressing medication for the rest of her life to reduce the risk that her body will reject the new kidney. She'll also likely need to take drugs to lessen the likelihood of infections, which are a risk that comes with immune-suppressing drugs.

"In the beginning, you're a walking pharmacy after kidney transplants, and eventually, you're on decreasing amounts of medication, but you're always on something to prevent rejection, even if it's only one drug, although often it's more than that," Shapiro says.